This invention relates in general to compositions to remove ice from surfaces and/or to prevent ice from forming on surfaces, and in particular to biobased deicing/anti-icing fluids.
De-icing/anti-icing fluids are used in many different applications, such as on roadways, sidewalks, airport runways, and other outdoor surfaces where icing is a problem. In one particular application, deicing/anti-icing fluids are used in the aircraft industry to control icing on the surfaces of planes or runways. Deicing involves the application of a deicing fluid onto ice that has already formed on the plane or runway in order to remove the ice. The deicing fluid lowers the freezing point of the ice so that it becomes a liquid rather than a solid. Anti-icing involves the application of an anti-icing fluid onto a surface of the plane or runway before ice is present, thereby lowering the freezing point of any precipitation that contacts the surface and preventing it from turning into ice.
Fluids based on propylene glycol and ethylene glycol are the most popular aircraft deicing/anti-icing fluids in use today. The glycol-based fluids are effective against ice, but they are considered to be harmful to the environment, particularly if applied in large volumes. There is a strong need for environmentally friendly deicing/anti-icing fluids that perform comparably to the glycol-based fluids.
Several patents disclose aircraft deicing/anti-icing fluids containing sorbitol and/or glycerol instead of propylene glycol or ethylene glycol. For example, U.S. Pat. No. 6,129,857 to Sapienza discloses aircraft deicing/anti-icing fluids containing sorbitol, water and other ingredients. U.S. Pat. No. 5,993,684 to Back et al. discloses aircraft deicing fluids containing glycerol, sorbitol and water, and optionally materials such as thickeners, antioxidants, pH adjusters, stabilizers, biocides, or corrosion inhibitors. International Patent Publication No. WO 01/29146 A1 to Westmark et al. discloses aircraft deicing fluids containing glycerol, nonionic surfactant, polysaccharide thickener, and water. There is still a need for improved deicing/anti-icing fluids.